It is well known for utility company servicemen to use high voltage detecting test sticks when in the field. Prior art test sticks have employed a neon filled gas tube which glows in the presence of high voltage over a predetermined value. The predetermined value is usually dependent upon the characteristics of the neon tube.
Typically, a terminal prong of the test stick is applied to or near a piece of energized electrical equipment. The potential difference between the equipment and ground causes a small current to flow through the terminal prong via a conductor to an electrode of the neon tube. If the potential and the frequency of the voltage alternations from the electrical energy applied to the electrode are of a suitable value, the tube will glow thereby detecting the presence of such energy. The field serviceman detects the visible glow of the neon tube indicating the high potential. An electrical test stick of the type described above is known from U.S. Pat. No. 1,906,644.
A problem associated with the neon tube test stick is that when used in the field, often times the glow of the tube is hard to detect due to the bright sunlight. U.S. Pat. No. 1,906,644 makes use of a sun shield formed from an insulating material which is secured around the neon tube. However, depending upon the angle at which the test stick is held, the sun shield still may not provide enough cover for the illumination to be detected by the field serviceman.
Another known device is the current sensing monitor described in U.S. Pat. No. 4,558,310 which discloses the use of both visible and audible indicators. However, the current sensing device is not designed to function as a potential indicator for the industrial applications of large public utility companies which detect very high voltage situations. Another low voltage detecting device, U.S. Pat. No. 2,586,806, discloses the use of an auxiliary voltage responsive device wired in parallel with the testing device and providing simultaneous indications of the presence of electrical potential. Again, the potential indicator is manufactured and calibrated for a low voltage range and is not suitable for high voltage applications.